Bituminous emulsion and its production



COMPOSITIONS, COATING OR PLASTIC.

natural on in suchas asphalt and asphalt progucts. uc% emulsions are used as bindings, adhesives, and coating compositions, as well as for impregnating and surfacing purposes.

It is the broad object of the present invention to produce improved bituminous emulsions specifically using sodium metasilicate in a ue us solu- "tlon as the gm'fifiifim agent. The emfisions so orme'd are quite stable and resist freezing and subsequent thawing without breaking. The emulsions are further readily formed and involve sodium metasilicate yielding strongly alkaline solutions which maintain a very high degree of alkalinity even when extremely dilute so that the emulsions may vary considerably in composition.

The emulsions are particularly valuable inasmuch as the sodium metasilicate acts as a st bilizin ent preventing the breaking of em slons when mixed with dirty stone, hard water, or the like.

Prior to a description of the emulsions forming the subject matter of the present invention it may be pointed out that the ordina so ium 'cates composing water glass arenot usefulasemulsifying agents although under certain conditions they form valuable additions to already formed emulsions or emulsions which are formed by the use of auxiliary "emulsifying agents. While ordinary sodium silicate has been suggested as an emulsifying agent, it is incapable of producing a satisfactory 'bituminous emulsion, since for effecting emulsification of the bitumen it must be used in such amount as to form a highly viscous solution resulting in the formation of a paste emulsion as compared to an emulsion having substantially low viscosity relative to the bitumen content, or the viscosity of the sodium silicate solution must be increased or apparently increased by the addition, for example, of a filler, which necessarily remains in the emulsion, increasing the viscosity thereof to the form of a paste and wholly disadvantageous for many uses for which bituminous emulsions are desirable. As a consequence ordinary sodium silicates have, as a practical matter, not been used alone for the formation of bituminous emulsions, but have rather been used merely in association with other emulsifying agents for cumulative efiect or effects otherthanas an emulsifler. As compared with these heretofore gensodium metasilicate bituminous emulsions of hi h bitumen content and, at the same in e, of high fluidity or relatively low viscosity may be produced a? my v WWW I j Patented Feb. 5, 1935 I l I 1,989,775 BITUMINOUS EMULSION AND ITS 7 PRODUCTION Preston B. Smith, Bahway, N. 1., assignor to The Barber Asphalt Company, Philadelphia, Pa., a la corporation of Pennsylvania No Application June 3, 1931;

Serial No. 541,941 15 Claims. (01. 134-1) This invention relates to bituminous emulsions erally welllmown sodium silicates, sodium and their manufacture inc uding e ons of metasilicate, Na2Si03.5Hz0 in aqueous solution itches, tars and tar-like substances, re s an ac ec y as an em ying agent producing er bituminous sub: ances 0 'art or and the stabilized emulsions to which reference has already been made. Further, with the use of 5 and without the necessity for the use of any other 1 mentioned has a H value of approximateg 11 i, while tfiat of the stronger is apprg xLrgatgly 12.5.

It is to be noted that even though the ercentage of sodium metasilicate in solution varies quite considerably, nevertheless, the hydrogen ion concentration varies but little.

The bituminous emulsion may be formed in numerous ways; for example, sodium metasilicate solution of a concentration wi'thin the range 'ibove mentioned may be mixed with asphalt using for the emulsification any of the fiichanical mixers or agitators now in common use for preparing bituminous emulsions. The percentage of emulsifying agent and bituminous substance may vary considerably, the bitumen forming, for example, from 40% to 75% of the emulsion. In general, the proportions are determined both by the physical properties desired for the finished emulsion and by the choice of mechanical means used to produce the emulsion, less emulsifier being required with a highly effective mechanical device than with a less effective one.

While. in ielesaml i a Q fii zgit i mre i e ess at'i-oil maybe readily produced usin u me u ii; u cute as an emulsifying agent, the concentration of the metasilicate agent in water in this case being above 1.8%.

Bituminous emulsions prepared in accordance with the invention are found to have the general properties of emulsions heretofore produced. Thus, the emulsions will have comparable stability to those produced with emulsifiers heretofore ordinarily used, desirable high fiuidiiw with high bitumen content, etc.

It will be obvious that the emulsions may be admixed with other substances to form final products and that the emulsions need not be formed using sodium metasilicate alone as the emulsifying agent. That is, other emulsifying agents which are not incompa 1 e W1 so um me icate may be additionally used.

While the above description has referred specifically to sodium metasilicate it is possible to use potassium or other lkali metasilicate instead of fie mum metasilicate 55 substantially the same results. However, by reason of its cheapness the use of sodium metasilicate is preferred.

What I claim and desire to protect by Letters Patent is:

1. A bituminous emulsion including as constituents bitumen and an aqueous solution containing alkali metasilicate as an emulsifying agent.

2. A bituminous emulsion including as constituents bitumen and an aqueous solution containing alkali metasilicate as an emulsifying agent, the emulsion being of oil-in-water type.

3. A bituminous emulsion including as constituents bitumen and an aqueous solution containing alkali metasilicate to the extent of 0.2% to 1.6%.

4. A bituminous emulsion including as constituents bitumen and an aqueous solution containing alkali metasilicate as an emulsifying agent and having a pH value between 11.6 and 12.5.

5. A bituminous emulsion free from solid material other than bitumen, high in bitumen content and of low viscosity relative to the bitumen content, including as constituents bitumen and an aqueous solution containing alkali metasilicate as an emulsifying agent.

6. A bituminous emulsion free from solid material other than bitumen, high in bitumen content and of low viscosity relative to the bitumen content, including as constituents bitumen and an aqueous solution containing alkali metasilicate as the sole emulsifying agent.

'I. A bituminous emulsion free from solid material other than bitumen within the range 40%-75% and of low viscosity relative to the bitumen content, incdluding as constituents bitumen and an aqueous solution containing alkali metasilicate as an emulsifying agent.

8. A bituminous emulsion free from solid material other than bitumen, high in bitumen content and of low viscosity relative to the bitumen content, including as constituents bitumen and an aqueous solution containing alkali metasilicate as an emulsifying agent, the emulsion being of the oil in water type.

9. The method of making a bituminous emulsion which includes intermixing bitumen in a fluid state with an aqueous solution containing alkali metasilicate as an emulsifying agent of low concentration, of high fluidity and free from suspended material.

10. The method of making a bituminous emulsion which includes intermixing bitumen in a fluid state with an aqueous solution containing alkali metasilicate in amount within about the range 0.1 %1.8%.

11. The method of making a bituminous emulsion including intermixing bitumen in a fluid state with an aqueous solution containing sodium metasilicate as an emulsifying agent of low concentration and high fluidity and having a pH value within about the range pH 11.6 to pH 12.0.

12. The method of making a bituminous emulsion which includes intermixing bitumen in a fluid state with an aqueous solution containing sodium metasilicate of a concentration within about the range 0.1%-1.8% and free from suspended material.

13. The method of making a bituminous emulsion which includes intermixing bitumen in a fluid state with an aqueous solution containing alkali metasilicate in amount about 1.6%.

14. The method of making a bituminous emulsion which includes intermixing bitumen in a fluid state with an aqueous solution containing sodium metasilicate in amount about 1.6%.

15. A bituminous emulsion including as constituents bitumen and an aqueous solution containing sodium metasilicate in amount of PRES'ION R. SMITH. 

